The present invention relates to an electrical connector system for use particularly, but not exclusively, in the oil industry. The electrical connector system is particularly suitable for use as a wellhead connector system used in subsea downhole environments for providing electrical connection through the wellhead into a tubular element with apertures for carrying electrical cables downhole.
Electrical connections are required in subsea equipment so that electrical signals can pass to the subsea completion systems allowing signals to be relayed between downhole transducers and the surface for example, from permanent monitoring equipment. The signals can also be used to provide information to allow intelligent completion control of wells. Electrical connections are typically provided in prior art systems using a vertical stab arrangement. This is an arrangement where tubular elements typically have a plurality of male electrical connectors extending from the end of one tubular element for mating with corresponding female electrical connectors on an adjacent electrical element. Although such vertical stab elements are commonplace and generally work well, they suffer from the significant disadvantage that careful orientation is required before the connections are made up otherwise, if an attempt is made to mate two adjacent pieces of equipment together when the connectors are out of registration, this can result in damage to the connectors, subsequent retrieval of part, or all, of the connecting equipment being necessary. Orientation is often time-consuming and difficult depending on the equipment used and the particular well conditions. A further disadvantage with the vertical stab arrangement is that it often requires multiple parallel channels to be made through each tubular element which is expensive and can be difficult when relatively thin walled elements are required leading to a restriction in the number of cables and consequently monitoring arrangements.
An object of the present invention is to provide an improved electrical connector system which obviates or mitigates at least one of the aforementioned disadvantages.
This is achieved in the most general sense by providing a circumferentially electrically conductor ring which is coupled to, and insulated from, a tubular subsea element such as a tubing hanger, partly by an elastomeric electrically insulating sealing element, surrounding the conductor ring. The conductor ring is coupled to an electrical annular connector and is adapted to receive an electrical connector of a horizontally mounted electrical connector assembly which is hydraulically activated to penetrate the elastomeric element in the direction transverse to the longitudinal axis of the tubular element.
The tubular element, such as a tubing hanger, is machined to receive the conductor ring assembly which includes a conductor ring. The tubular element and conductor ring fit within a wellhead or tubular casing which has an aligned aperture for receiving the horizontally mounted electrical connector assembly. The electrical connector assembly is actuatable to cause an electrical connector/penetrator to be moved towards the conductor ring assembly so as to penetrate the elastomeric insulating ring and consequently makes electrical contact with the conductor ring to complete an electrical connection from the electrical connector assembly through the conductor ring to the annular connector which, in turn, is coupled to a cable connected to downhole transducers or electrical equipment.
Removal of the electrical connector/penetrator results in the elastomeric ring self-sealing to prevent well fluids connecting with the conductor ring and providing an electrical short circuit.
The electrical connector/penetrator is hydraulically operated and is also spring-biased such that in the absence of any hydraulic pressure to the connector assembly, the spring is biased to force the electrical penetrator into contact with the conductor ring to provide an electrical contact in the event of hydraulic pressure failure.
According to a first aspect of the present invention, there is provided a wellhead electrical connector system for use with a wellhead, said electrical connector system having a tubing hanger for location in said wellhead, said tubing hanger having a circumferential electrical conductor ring assembly disposed at one end thereof, said electrical conductor ring assembly having an electrical conductor ring which is electrically insulated from the tubing hanger housing, a circumferential elastomeric sealing ring disposed about the said electrical conductor ring for electrically insulating said conductor ring from the tubing hanger and from the external environment, said tubing hanger having at least one electrical connector disposed in the tubular wall thereof for conveying electrical signals to electrical conductors adapted to be coupled thereto, said elastomeric insulated sealing ring being penetrable by an energisable electrical connector coupled to the wellhead to contact said conductor ring and provide an electrical connection from the energisable electrical connector through the tubing hanger to said at least one electrical connector disposed within said tubing hanger.
Preferably, the tubing hanger has a machined upper end for receiving the conductor ring assembly, such that when the conductor ring assembly is fitted to the tubing hanger, the external diameter of the tubing hanger is substantially the same as prior to machining the tubing hanger.
Preferably also, the conductor ring assembly has an annular structure with the conductor ring and elastomeric ring being retained between a lower conductor ring housing and an upper retaining ring, the elastomeric element being forced onto the conductor ring via an upper retainer ring acting through a spring onto a spring energiser ring which abuts the circumferential elastomeric sealing ring. The entire assembly is retained by an upper annular hanger lock ring which forces the retainer ring and spring and spring energiser ring against the elastomeric element.
Conveniently, the elastomeric ring is shaped to allow expansion when compressed by the retainer ring so as to provide effective sealing against the interior surface of the wellhead and minimise the intrusion of well fluids between the elastomeric sealing ring surface and the opposed surface of the interior of the wellhead.
Conveniently, the springs are wave or disc springs. Preferably, the elastomeric element is a machined or moulded element.
Conveniently, the electrical connector system is electrically coupled to a multi-way connector (i.e. Tronic, U.K.) for conveying electrical signals from a source external to the connector assembly through the connector assembly to the conductor ring when in use. Advantageously, the electrical penetrator is coupled to a manual/ROV override boss which allows the penetrator to be disengaged from the conductor ring in the event of hydraulic failure.
According to a further aspect of the present invention, there is provided a method of providing electrical connection through a tubular element, said method comprising the steps of,
machining a tubular element to provide an annular recessed area,
fitting an electrical conductor ring assembly into the recessed area,
disposing an electrical connector assembly having a moveable electrical connecting element at a predetermined location external to the tubular element,
actuating the electrical connecting element in a direction substantially transverse to the longitudinal axis of the tubular element to make electrical contact with the conductor ring assembly whereby electrical connection through said conductor assembly such that electrical signals pass from outside the tubular element in a transverse direction via said conductor ring assembly to electrical connectors within said tubular element.
Preferably, the method includes the step of biasing the electrical connector assembly such that in the event of hydraulic failure or actuation of the electrical connector penetrator, resilient means urge the electrical penetrator into electrical contact with said conductor ring.
Preferably, said method includes the step of sealing said conductor ring by said elastomeric ring upon removal of the electrical penetrator.
Preferably, the tubular element is a tubing hanger disposed in a wellhead.
According to a further aspect of the invention, there is provided an electrical conductor ring assembly for use with a downhole tubular element having an electrical connector in a wall thereof and at least one annular bore for receiving an electrical conductor, said conductor ring assembly being adapted to be coupled to said tubular element, said conductor ring assembly having a generally circumferential conductor ring element, a generally circumferential insulating element for electrically insulating said conductor ring assembly from the tubular element, a generally circumferential elastomeric electrically insulating element adapted to be disposed radially externally to the conductor ring assembly for effectively sealing the conductor ring assembly from external well fluids, the conductor ring assembly having upper and lower support means for urging said elastomeric element into contact with said conductor ring, said conductor ring assembly being adapted to be coupled to an electrical conductor for fitting into said bore of said tubular element, said elastomeric sealing ring being resilient such that it deforms to allow an electrical penetrator to make electrical contact with said conductor ring, and upon the removal of said electrical penetrator, the elastomeric sealing element recovers to seal the previously penetrated area.
According to a yet further aspect of the present invention there is provided a non-orientation required electrical connector system for use with concentric tubular elements coupled together for use within a well, said electrical connector system having a first and a second tubular element for location in said well, said first tubular element having a first coupling portion of a first diameter having a generally circumferentially extending electrical conductor ring assembly disposed at said portion, said electrical conductor ring assembly having an electrical conductor ring which is electrically insulated from the first tubular element housing, a generally circumferential elastomeric sealing ring disposed about the said electrical conductor ring for electrically insulating said conductor ring from the first tubular element and from the external environment, said first tubular element having at least one electrical connector disposed in a wall of said first tubular element thereof for conveying electrical signals to electrical conductors adapted to be coupled thereto, said second tubular element having a second coupling portion of a second diameter different from said first diameter portion and being adapted to be coupled to the first coupling portion of said first tubular element, said second tubular element having an energisable electrical connector coupled thereto, the arrangement being such that when said first and second tubular elements are coupled together at said first and second coupling portion, said energisable electrical connector penetrates said elastomeric insulated sealing ring to contact said conductor ring and provide an electrical connection from the energisable electrical connector from the second tubular element to said at least one electrical conductor within said first tubular element.